Everywhere you look these days, cities have either Highlinitis or Bilbaosis, trying to imitate the magic that attracts thousands of people and revitalizes cities and neighborhoods. But can you really compare this project in Seoul to the High Line?
It is a short length of elevated overpass (938 meters or .6 of a mile) that is no longer used as it isn't safe for heavy vehicles anymore. But it is strong enough for trees and people, and it is being turned into a Skygarden by MVRDV. Their work is often over the top, (like their hallucinogenic Rotterdam market) so it makes sense that they would win the competition to go over the top of Seoul.
MVRDV writes that "many viaducts and pedestrian overpasses in Asian cities are purely functional elements, but due to the scale of the Seoul Station Overpass which was built for vehicle traffic, an opportunity exists to create a unique public space in the heart of Seoul." Dezeen notes that "It's the latest in a series of proposed landscape projects inspired by the High Line" but it is a very different thing;
The high line is surrounded by stuff to look at and has lots of access points. This overpass will act as a useful shortcut for people who no longer have to walk around the station to get to the big Namedaemun Market, but doesn't provide much of a view of anything but tracks and highways leading into the railway station. The high line provides and outward view; this is far more introspective and inward looking.
Fortunately that architects are giving people something to look at; a "a library of local plants, a Korean arboretum of species planted in ‘neighbourhoods’" and " tea cafés, flower shops, street markets, libraries and greenhouses."
Highlinitis and Bilbaosis are terrible urban diseases where good ideas that work in one place spread and infect other cities where they do not have the same magical effect. However this is a useful bridge that will get pedestrians across this vast sea of rail lines in style and comfort. It looks like it will be magical in its own, original way.
See also Matt Hickman on MNN for a different view.